Refrigerating compressor and refrigerating device using the same

ABSTRACT

A refrigerating compressor includes a hermetic container accommodating oil, a motor accommodated in the container, a compressor unit provided under the motor and driven by the motor, and a vibration-proof cover. The compressor unit has a crankshaft including a main shaft and an eccentric section, a cylinder block, a piston, a connecting rod and a feed oil pipe. The cylinder block has a bearing to support the main shaft rotatably and a cylinder. The piston reciprocates in the cylinder. The connecting rod connects the piston to the eccentric section. The feed oil-pipe is fixed to eccentric section and an end thereof is dipped in oil. The vibration-proof cover is fixed to the cylinder block and surrounds the feed oil pipe with a given distance in between.

TECHNICAL FIELD

The present invention relates to a refrigerating compressor to be used in a refrigerator-freezer or the like, and it also relates to a refrigerating device using the same.

BACKGROUND ART

A conventional refrigerating compressor including a feed oil pipe dipped in oil is disclosed for instance in Unexamined Japanese Patent Publication No. H11-303740. The conventional refrigerating compressor is described hereinafter with reference to the accompanying drawings.

FIG. 5 shows a vertical sectional view of the conventional refrigerating compressor, and FIG. 6 shows an enlarged sectional view of an essential part of FIG. 5. Hermetic container 1 accommodates oil 2 and motor 3. Compressor unit 4 driven by motor 3 is accommodated, under motor 3, in hermetic container 1.

Compressor unit 4 has cylinder block 7 including cylinder 5 and bearing 6; and crankshaft 10 including eccentric section 8 and main shaft 9 which is supported by bearing 6. Eccentric section 8 of crankshaft 10 is connected to piston 11 via connecting rod 12. Piston 11 is inserted reciprocally in cylinder 5.

Valve plate 14 seals an opening end of cylinder 5, and discharge valve 13 is provided on valve plate 14 on the opposite side to cylinder 5. Valve plate 14 has suction valve 15. A first end of suction muffler 17 communicates with suction valve 15, a second end of suction muffler 17 opens to hermetic container 1 via sound deadening space 16.

Eccentric section 8 has feed oil pipe 18 at its lower end, and a first end of feed oil pipe 18 is press-fitted to eccentric section 8 and a second end thereof is dipped in oil 2. Feed oil pipe 18 is formed of a steel pipe, and is bent so as to form a V-shape including an obtuse angle such that the second end dipped in oil 2 is positioned at the rotating center of main shaft 9.

The operation of the refrigerating compressor having the foregoing structure is described hereinafter. The spin of crankshaft 10 by motor 3 is transmitted to connecting rod 12, so that piston 11 reciprocates. This reciprocation sucks refrigerant into suction muffler 17, and intermittently sucks the refrigerant into cylinder 5 via suction valve 15. The refrigerant flows through an outer cooling circuit (not shown) and is temporarily released into hermetic container 1 before it is sucked into suction muffler 17. The refrigerant sucked into cylinder 5 is compressed by piston 11, and pushes discharge valve 13 of valve plate 14 open, so that the refrigerant is discharged again into the outer cooling circuit. Oil 2 stored in container 1 is drawn through feed oil pipe 18 by centrifugal force of feed oil pipe 18 placed at the lower end of eccentric section 8 and is delivered to respective sliding sections of compressor unit 4.

In the foregoing structure, eccentric section 8 of crankshaft 10 is vibrated by large intermittent loads applied from connecting rod 12 when compressor unit 4 compresses the refrigerant, so that eccentric section 8 repeats bending deformation. The vibration of eccentric section 8 travels to feed oil pipe 18. Then feed oil pipe 18 is vibrated and thus generates resonance sound.

In addition, feed oil pipe 18 rotates in oil 2, thereby agitating oil 2. Oil 2 collides with structural elements of the refrigerating compressor in hermetic container 1, and the flow of oil 2 is thus disturbed, so that no neat eddy is formed. In this status, the refrigerant dissolved in oil 2 foams. This foam collides with feed oil pipe 18 following the disturbance of oil 2, thereby vibrating feed oil pipe 18 and generating the resonance sound. This phenomenon is conspicuous particularly when the refrigerant such as hydrocarbon that tends to dissolve much amount in oil 2 is used.

The vibration due to the resonance of feed oil pipe 18 travels to hermetic container 1 via oil 2, and radiates to the outside of container 1 as noises, so that the refrigerating compressor becomes noisy.

DISCLOSURE OF THE INVENTION

The present invention aims at providing a refrigerating compressor whose vibration due to the resonance of feed oil pipe travels little to the hermetic container, thereby causing lower noises. The refrigerating compressor of the present invention has a hermetic container accommodating oil; a motor accommodated in the hermetic container; a compressor unit disposed under the motor, accommodated in the container, and driven by the motor; and a vibration-proof cover. The compressor unit includes a crankshaft, a cylinder block, a piston, a connecting rod, and a feed oil pipe. The crankshaft has a main shaft and an eccentric section. The cylinder block has a bearing for supporting the main shaft rotatably, and a cylinder. The piston reciprocates in the cylinder. The connecting rod connects the piston to the eccentric section. The feed oil pipe is fixed to the eccentric section, and one of its ends is dipped into the oil. The vibration-proof cover is fixed to the cylinder block, and surrounds the feed oil pipe with a given distance in between. This structure allows isolating the resonance sound traveling from the feed oil pipe to the hermetic container, so that a refrigerating compressor with low noises is obtainable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a vertical sectional view of a refrigerating compressor in accordance with an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an essential part of the refrigerating compressor shown in FIG. 1.

FIG. 3 is a plane sectional view of the refrigerating compressor shown in FIG. 1.

FIG. 4 is a view of a refrigerating cycle of a refrigerating device employing the refrigerating compressor shown in FIG. 1.

FIG. 5 shows a vertical sectional view of a conventional refrigerating compressor.

FIG. 6 is an enlarged sectional view of an essential part of the conventional refrigerating compressor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

An exemplary embodiment of a refrigerating compressor of the present invention is demonstrated hereinafter with reference to the accompanying drawings. This embodiment does not limit the invention.

FIG. 1 shows a vertical sectional view of the refrigerating compressor in accordance with an embodiment of the present invention. FIG. 2 is an enlarged sectional view of an essential part of the refrigerating compressor. FIG. 3 is a plane sectional view of the refrigerating compressor. Refrigerating compressor 50 includes hermetic container 101, motor 106, compressor unit 107, and vibration-proof cover 125.

Hermetic container 101 stores oil 102 composed of mineral oil at its bottom, and is filled with refrigerant 103 composed of hydrocarbon such as R600a (isobutane). Hermetic container 101 accommodates motor 106 having stator 104 and rotor 105, and compressor unit 107 driven by motor 106. Compressor unit 107 is placed under motor 106.

A structure of hermetic container 101 is described hereinafter. Hermetic container 101 includes lower container 108 and upper container 109 both formed by drawing hot-rolled steel sheet or the like, and lower and upper containers 108 and 109 are welded at junction 110 by electric welding. Lower container 108 is equipped with discharge pipe 111 and suction pipe 112 both connected to the refrigerating cycle detailed later and shown in FIG. 4.

Next, a structure of compressor unit 107 is described hereinafter. Crankshaft 113 includes main shaft 114, rigidly inserted into rotor 105 of motor 106, and eccentric section 115. Cylinder block 116 includes bearing 117 for supporting main shaft 114 of crankshaft 113 rotatably, and cylinder 120, into which piston 118 is inserted for forming compression room 119. Cylinder block 116 supports stator 104. Eccentric section 115 of crankshaft 113 is connected to piston 118 by connecting rod 121.

Feed oil pipe 123 (hereinafter referred simply as “pipe 123”) attaches to the lower end of eccentric section 115 such that a first end of pipe 123 is press-fitted to the lower end of eccentric section 115 and a second end is dipped in oil 102 and placed on an extension line of the rotation axis of main shaft 114. Pipe 123 is formed of a steel pipe such as carbon steel pipe for machine construction, and bent at bent section 122 to form a V-shape including an obtuse angle. Feed oil hole 124, into which pipe 123 is press-fitted, communicates with respective sliding sections of compressor unit 107.

FIG. 4 shows a refrigerating cycle of a refrigerating device including refrigerating compressor 50. Refrigerating compressor 50 is coupled to heat exchanger 60 on heat absorption side (hereinafter simply referred to as “heat exchanger 60”), namely low-pressure side of the refrigerating cycle, by suction pipe 112 shown in FIG. 3, thus heat exchanger 60 is configured to run refrigerant having undergone heat-absorption to refrigerating compressor 50. Refrigerating compressor 50 is also coupled to heat exchanger 70 on heat radiation side (hereinafter referred simply as “heat exchanger 70”), namely high-pressure side of the refrigerating cycle, by discharge pipe 111. Compressed refrigerant 103 is discharged from discharge pipe 111, and is sent to heat exchanger 70 for radiating heat, then returns to heat exchanger 60 via expansion valve 80 for absorbing heat. The refrigerating device is thus formed.

Next, vibration-proof cover 125 disposed in lower container 108 is described hereinafter. Vibration-proof cover 125 is shaped like a cup and is placed inside lower container 108 with a given distance to the bottom, and at the same time it surrounds pipe 123 with a given distance in between. Vibration-proof cover 125 is made of the material such as, for instance, metal or polybutylene terephthalate resin that is not swelled by refrigerant 103 or oil 102. Where, “a given distance” can be a distance long enough for vibration-proof cover 125 to prevent from touching tube 123 during operation of refrigerating compressor 60.

Vibration-proof cover 125 has fixing section 126, a portion of the cup-like form bent outward, and is fixed to the bottom of cylinder block 116 at fixing section 126 by bolt 128.

The operation of the refrigerating compressor having the foregoing structure is demonstrated hereinafter. Motor 106 in operation prompts rotor 105 to rotate crankshaft 113, thereby reciprocating piston 118 in cylinder 120 via connecting rod 121. This motion allows refrigerant 103, flowing from heat exchanger 60 shown in FIG. 4, to be sucked into compression room 119. through suction pipe 112. Refrigerant 103 flowing into compression room 119 is compressed by piston 118 reciprocating in cylinder 120, and is then discharged from discharge pipe 111 to heat exchanger 70 shown in FIG. 4.

Pipe 123 rotates together with crankshaft 113. The first end of pipe 123 is press-fitted into eccentric section 115 roughly at the center. The second end of pipe 123 is dipped in oil 102 and positioned on the extension line of the rotation axis of main shaft 114, so that the centrifugal force due to the rotation works on oil 102 in pipe 123. This centrifugal force works as pumping force which delivers, via feed oil hole 119, oil 102 inside vibration-proof cover 125 to respective sliding sections of compressor unit 107.

Compression load applied to piston 118 allows applying loads intermittently to eccentric section 115 of crankshaft 113, which thus repeats bending deformation. This deformation of eccentric section 115 travels as vibration to pipe 123, thereby vibrating pipe 123, so that pipe 123 generates resonance. However, in refrigerating compressor 50, vibration-proof cover 125 cuts off the travel of the resonance of pipe 123 to hermetic container 101. As a result, the vibration traveling from pipe 123 to lower container 108 is attenuated, and the noise to be radiated from hermetic container 101 to the outside is suppressed to a lower level.

Vibration-proof cover 125 is preferably made of vibration damping material such as polybutylene terephthalate resin. This can create a greater amount of attenuation. Vibration-proof cover is placed inside lower container 108 with a given distance to the bottom, so that no parts vibrates hermetic container 101 directly and the noise radiated to the outside of hermetic container 101 can be suppressed to an excessively low level.

It is preferable that communicating hole 129 having a smaller diameter than an inner diameter of pipe 123 is provided at the lower part of vibration-proof cover 125. This structure allows continuous supply of oil 102 from the outside of vibration-proof cover 125 through communicating hole 129 into the inside of vibration-proof cover 125 even if the surface of oil 102 inside vibration-proof cover 125 lowers. The diameter of communicating hole 129 is smaller than the inner diameter of pipe 123 of the order of not to causing oil shortage inside vibration-proof cover 125. Therefore, little vibration due to pipe 123 travels through communication hole 129, so that the resonance of pipe 123 can be cut off by vibration-proof cover 125 very effectively.

Upper end 130 of vibration-proof cover 125 preferably extends upward and exceeds the surface of oil 102. This structure allows oil 102 inside vibration-proof cover 125 to communicate with oil 102 in hermetic container 101 only through communicating hole 129, so that the resonance of pipe 123 can travel only through communicating hole 129.

Next, the situation where bubbles of refrigerant 103 collide with pipe 123 is demonstrated hereinafter. When refrigerating compressor 50 starts operating, the inside of hermetic container 101 is decompressed. As a result, refrigerant 103 dissolved in oil 102 during the halt of refrigerating compressor 50 starts foaming. The bubbles of refrigerant 103 generated at this time draw an eddy-like path following the rotation of pipe 123, and the bubbles are drawn to the tip of pipe 123 together with oil 102. At this time, when the bubbles is drawn together with oil 102 disturbed around pipe 123 to the tip of pipe 123, the bubbles collide with the inner and outer walls of pipe 123, so that pipe 123 is greatly vibrated.

Considering the status discussed above, it is preferable that the inner wall of vibration-proof cover 125 shapes like a smooth body of revolution. The shape is free from inward projections or the like. Furthermore, the body of revolution formed by revolving on an extension line of the rotation axis of main shaft 114 would be preferable. This shape allows oil 102 inside vibration-proof cover 125 to rotate in a conical shape without disturbance following the rotation of pipe 123. As a result, drawing a smooth circle, the bubbles of refrigerant 103 in oil 102 approach to the tip of pipe 123, so that collisions between the bubbles and the inside or outside wall of pipe 123 decrease drastically. Oil 102 including the bubbles is thus smoothly drawn into pipe 123, and the resonance of pipe 123 decreases also drastically.

Elastic body 127 formed of nitrile rubber or the like is preferably provided between vibration-proof cover 125 and cylinder block 116. Elastic body 127 cuts off vibrations traveling from compressor unit 107 to vibration-proof cover 125 via cylinder block 116 during its operation, which prevents the resonance of vibration-proof cover 125 and lowers energy to vibrate hermetic container 101 greatly, so that the noise radiated to the outside of container 101 is suppressed to a very low level.

Refrigerant 103 such as hydrocarbon and oil 102 such as mineral oil or alkyl benzene are mutually soluble with each other, so that refrigerant 103 dissolved in oil 102 during the halt of refrigerating compressor 50 sometimes abruptly starts foaming when refrigerating compressor 50 starts operating. Even after this abrupt foaming is finished, refrigerant 103 in oil 102 more or less foams successively during the operation of refrigerating compressor 50.

In this embodiment, refrigerant 103 easy to foam is combined with oil 102. A noise level of hermetic container 101 due to resonance can be lowered even if the resonance of pipe 123 frequently occurs due to the collision between the bubbles and pipe 123 with this combination. This is because vibration-proof cover 125, formed of the vibration damping member, efficiently damps the vibration traveling in oil 102, thereby reducing drastically the vibration transmitted to the outside of vibration-proof cover 125. In addition, it must be a contribution to the result that vibration-proof cover 125 is placed inside lower container 108 with a given distance, thereby reducing the energy to vibrate hermetic container 101 directly to a very low level. As discussed above, even use of pipe 123, weakening the noise of refrigerating compressor 50 to an excessively low level is allowed. Pipe 123 made of a steel pipe such as a carbon steel pipe for machine construction is just bent at bent section 122 to form a V-shape including an obtuse angle, so that pipe 123 is obtainable at a high productivity.

Pipe 123 violently agitates oil 102, which thus splashes from the oil surface, so that the oil drops scatter. This particular case is described hereinafter. When pipe 123 rotates in oil 102 during the operation of refrigerating compressor 50, the centrifugal force works on oil drops attached to the outer wall of pipe 123. This centrifugal force sometimes produces oil drops splashed and separated from the oil surface of oil 102. The oil drop, in general, splashes along the outer rim of pipe 123 and collides with hermetic container 101 or compressor unit 107, thereby causing noises.

Upper end 130 of vibration-proof cover 125 preferably extends upward and exceeds bent section 122 of pipe 123. This structure allows the inner face of vibration-proof cover 125 to catch the oil drops splashed by pipe 123, so that the scatter of oil drops is prevented from colliding with hermetic container 101 or compressor unit 107. As a result, noises can be prevented.

In this embodiment, vibration-proof cover 125 made of resin such as polybutylene terephthalate resin is used; however, vibration damping steel plate or rubber such as nitrile-butadiene rubber can be used instead of the resin, and these materials produce an advantage similar to what is discussed above. Cold-rolled steel sheet, which is inexpensive and highly formable, can be used as the material of vibration-proof cover 125 with an advantage similar to the foregoing one.

INDUSTRIAL APPLICABILITY

A refrigerating compressor of the present invention is useful for a refrigerating device to be used in a home-use refrigerator-freezer which requires quiet operation, and it is applicable to business-use refrigerator-freezers to be used in hotels or a medical care industry.

REFERENCE NUMERALS IN THE DRAWINGS

-   50 Refrigerating compressor -   60 Heat exchanger on heat absorption side -   70 Heat exchanger on heat radiation side -   80 Expansion valve -   101 Hermetic container -   102 Oil -   103 Refrigerant -   104 Stator -   105 Rotor -   106 Motor -   107 Compressor unit -   108 Lower container -   109 Upper container -   110 Junction -   111 Discharge pipe -   112 Suction pipe -   113 Crankshaft -   114 Main shaft -   115 Eccentric section -   116 Cylinder block -   117 Bearing -   118 Piston -   119 Compressor room -   120 Cylinder -   121 Connecting rod -   122 Bent section -   123 Feed oil pipe -   124 Feed oil hole -   125 Vibration-proof cover -   126 Fixing portion -   127 Elastic body -   128 Bolt -   129 Communicating hole -   130 Upper end 

1. A refrigerating compressor comprising: (a) a hermetic container accommodating oil; (b) a motor accommodated in the hermetic container; (c) a compressor unit disposed under the motor, accommodated in the hermetic container, and driven by the motor, the compressor unit including: (c-1) a crankshaft having a main shaft and an eccentric section; (c-2) a cylinder block having a bearing supporting the main shaft rotatably, and a cylinder, (c-3) a piston reciprocating in the cylinder; (c-4) a connecting rod coupling the piston with the eccentric section; (c-5) a feed oil pipe attached to the eccentric section and having an end dipped into the oil; and (d) a vibration-proof cover fixed to the cylinder block and surrounding the feed oil pipe with a given distance in between.
 2. The refrigerating compressor according to claim 1, further comprising an elastic body provided between the vibration-proof cover and the cylinder block.
 3. The refrigerating compressor according to claim 1, wherein the vibration-proof cover is provided with a communicating hole having a diameter smaller than an inner diameter of the feed oil pipe.
 4. The refrigerating compressor according to claim 3, wherein an upper end of the vibration-proof cover extends upward and exceeds a surface of the oil.
 5. The refrigerating compressor according to claim 1, wherein the vibration-proof cover is formed of vibration damping material.
 6. The refrigerating compressor according to claim 1, wherein the feed oil pipe is formed of steel pipe, has a bent section, and is shaped as a V-shape including an obtuse angle.
 7. The refrigerating compressor according to claim 6, wherein an upper end of the vibration-proof cover extends upward and exceeds the bent section.
 8. The refrigerating compressor according to claim 1, wherein an inner wall of the vibration-proof cover is shaped as a body of revolution.
 9. The refrigerating compressor according to claim 1, wherein the oil is one of mineral oil and alkyl benzene, and the compressor compresses hydrocarbon as refrigerant.
 10. A refrigerating device comprising: the refrigerating compressor as defined in claim 1; a heat exchanger on heat radiation side coupled with the refrigerating compressor; an expansion valve coupled with the heat exchanger on heat radiation side; and a heat exchanger on heat absorption side coupled with the expansion valve configured to run refrigerant having undergone heat-absorption to the refrigerating compressor.
 11. The refrigerating device according to claim 10, wherein the refrigerant is hydrocarbon, and the oil is one of mineral oil and alkyl benzene. 